Process of marbling or decorating leather.



NITED STATES GEORG COLLIN, OF BERLIN, GERMANY, ASSIGNOR TO THE FIRM OF WV.- COLLIN, OESAME PLACE.

PROCESS OF MARBLING OR DECORATING Ll- IATHER.

SPECIFICATION forming part of Letters Patent No. 670,396, dated March 19, 1901.

Application filed May 8, 1900.

To all whom it may concern.-

Be it known that I, GEORG COLLIN, a citizen of Prussia, Empire of Germany, residing at Berlin, in the Province of Brandenburg,

Germany, have invented certain new and use-- ful Improvements in Processes for Marbling or Decorating Leather, of which the following is a full specification.

This invention relates to a process for marbling or decorating leather in various tints or shades of color,whereby very fine effects from an artistic point of view may be obtained.

The process is destined to be employed on leather which is to be dyed with artificial dyestuffs derived from coal-tar.

If it be desired to dye tanned leather with coal-tar dyes, it is usually quite sufficient to steep the leather into the solution of the dye or to bring a solution of the dye on the surface of the leather by means of a brush. The leather need not be mordanted in order to fix the dye. However, it is only possible to dye leather in a uniform color by that method. If it be required to produce various shades of one color, so that the surface may appear, as it were, in a marbled state, another process must be applied, which forms the object of the present invention.

It has been said that artificial dyestufis derived from coal-tar have the property of fixing themselves to the surface of tanned leather without the use of mordants. It therefore becomes necessary to treat various places on the leather with solutions of certain chemical salts, so that they do not take the dye in the subsequent treatment with solutions of coaltar dyes. This is effected in the following manner: The surface of the tanned leatherto be treated is moistened with water and the excess moisture removed by rubbing with a dry cloth or the like. Those parts of the surface which at the conclusion of the treatmentc'. 6., after the coloring-are to appear bright are then dotted, sprinkled, or brushed with an alum solution (about eighty grams of crystallized potash-alum in one liter of water) or a stannous-chlorid solution, (forty grams of SnOl +2H,O in one liter of water,) and the surface of the leather is allowed to dry at the ordinary temperature. The leather is then Serial No. 15,963.

covered with a dilute alkaline solution (soda or potash lye of about the strength of 10 Twaddell) for a few minutes-say two or three miuutes-the soleobject of which is to close the pores of the leather. This is of importance in order that the dye which is afterward applied may not penetrate the'leather and cause dark patches. The surplus alkaline lye is then removed by rubbing,and alum solution or stannous-chlorid solution of the same strength as above is again sprinkled on the damp surface in order to make the desired bright places of the marbling appear very strongly. When the surface of the leather is once more quite dry, the leather is rubbed over with the solution of the selected coal-tar dye, the strength of which varies with the depth of color desired. The places mordanted with the alum or tin solution do not take the dye, and therefore remain bright, by which meansa marbling is produced in a very effective manner.

The surface to be decorated is not infrequently provided with the outlines of a picture, which may be applied to the leather by leather stamping or cutting work or the like. In order to protect the picture and to exclude it from the treatment hereinbefore described, it must be covered in the ordinary manner with a suitably cut-out templet. The picture (Specimens) may also be decorated before orafterward,

and in this manner a picture with a marbled background is obtained.

The above process can be applied with tanned cowhide, calfskin, or sheepskin. Experiments have shown that the process gives splendid results with the following colors:

vBasic dyes: phosphin N, fast brown G, chrysoidin, auramin II, cerise 2 B, methylviolet 2 R, aethyl-green, malachite-green,

eosin, erythrosin B, rhodamin B M, methylone-blue 2 B, and brilliant saifranin G.

Acid dyes: acid yellow G, fast brown N, ponceau 4 R. B, ponceau B O, bordeaux B, guinea-green B, water-blue R, and quinolinyellow.

It has been mentioned that in place of alum stannous chlorid may be employed for merdanting the leather. For the so-called basic dyes either alum or stannous chlorid may I00 be used, whereas for the acid dyes only stannous chlorid may be employed in order to obtain good results.

If it be desired to shade the pictures or designs cut or stamped in the leather surface, so as to cause them to stand out better from the surface, those parts of the picture or design which are to appear clear yellow are mordanted with an alum solution, (about eighty grams of potash alum in one liter of water,) while the places which are to assume a darker tone are treated with an alkaline-bichromate solution, (about twenty-ii ve grams potassium bichromate in one liter of water,) the concentration of the solution varying according to the depth of color desired. The pictures or designs may also be brushed with an iron solution, (about thirty grams of ferrous sulfate in one liter of water,) and the gray to grayblack colori ng of iron tannate resulting there by may be treated with a dilute solution of some suitable acid. If hydrochloric acid be used, a very clear yellow tone is obtained, oxalic acid produces a flesh color shading into rose, and picric acid gives a yellowish-green tone, dac. Certain other saltssuch, for instance, as zinc chlorid, aluminium chlorid, cupric chlorid, aluminium sulfate, and other like saltsprod uce actions similar to those of alum or stan nous chlorid; but the effects produced by the solutions of these salts are not by far so permanent as those obtained with alum or stannous chlorid.

Leather treated in this manner may be worked up for many different articles, such as albums, writing-pads, fancy goods in general, furniture-leathers, and the like.

Having now particularly described and as certained the nature of the said invention and in What manner the same is to be performed, I declare that What I claim is A process for decorating leather with coaltar dyes, which consists in the following steps: applying solutions of metallic salts to the leather, as set forth, whereby portions of the same are protected against the subsequentlyapplied dye; then treating the leather with an alkaline solution; then again with a protecting solution, as before; then applying a solution of a coal-tar dye whereby only the unprotected portions of the leather are colored, all substantially as described.

In witness whereof I have hereunto set my hand in presence of two witnesses.

GEORG COLLIN.

Witnesses:

WOLDEMAR HAUPT, HENRY IIASPER. 

